Method of making piston ring stock



May 13, 1958 s. H. NORTON 2,834,095

METHOD OF MAKING PI-STON RING STOCK Original Filed Au 18; 1949 I '7Sheets-Sheet 1 v.E gti fnz enfur Same! fffl ortazz Hill 5 May 13, 1958s. H. NORTON 2,834,096

METHOD OF MAKING PISTON RING STOCK Original Filed Aug. 18, 1949 7Sheets-Sheet 2 ll NH J ;9

lmm I U.

[171 217 far May 13, 1958 s. H. NORTON METHOD OF MAKING PISTON RINGSTOCK '7 Sheets-Sheet 3 Original Filed Aug. 18, 1949 May 13, 1958 s. H.NORTON METHOD OF MAKING PISTON RING STOCK 7 Sheets-Sheet 4 OriginalFiled Aug. 18, 1949 y 1958 s. H. NORTON 2,834,096

' METHOD OF MAKING PISTON RING STOCK 3? LE w J \Q i g Z9 I I r44) i I 29:56 H 57 l i]! I; 35 54 I ll! 51 5,3 HVE'H UP 43 44 42 SamzzeZH M1 '7Sheets-Sheet '7 S. H. NQRTON METHOD OF MAKING PISTON RING STOCK May 13,1958 Original Filed Aug. 18, 1949 [17 1 517 far Samuel H M1 50 messMETHOD OF MAKES PISTON RING STOCK Samuel H. Norton, University Heights,Ohio, assignor to Thompson Products, inc, Cleveland, Ohio, a corporationof Ohio Unite 1 Claim. (Cl. 29-1565) The invention relates toimprovements in methods for forming piston ring stock from flatcontinuous strip piston ring material, and is a division of applicationSerial No. 111,311 filed on August 18, 1949, now Patent No. 2,699,209.

A principal object of my invention is to provide a new and improvedmethod for forming from flat continuous strip material, piston ringstock U-shaped in cross-section having a central slotted web andparallel spaced alternately slit crowns extending from opposite sidesthereof.

A further object of my invention is to provide a new and improved methodfor forming U-shaped piston ring stock having a central slotted web andparallel spaced alternately slit crowns extending from opposite sidesthereof in a series of intermittent operations, each one of which issimultaneously performed at different longitudinally spaced places alongthe strip material.

A further object of my invention is to provide a new and improved methodof making a metal strip generally U-shaped in crosssection and having aladder-like Web with parallel slit legs extending from each side thereofby piercing parallel spaced slots along the center of a metal strip andsupporting the unpunched portions of the strip at the advance end of thestrip at longitudinally spaced areas with alternate intermediateportions of the pierced strip unsupported, shearing the unsupportedportions from the supported portions and bending the unsupportedportions to form tabs guiding the supported portions, and then bendingthe unbent portions into alignment with the bent portions.

In carrying out my invention I pierce a predetermined length ofstriptransversely of the strip, to form a plurality of parallel spacedcross bars. I then advance the strip an increment in length and engagethe pierced portion thereof, to locate the strip and at the same timepierce a next succeeding portion of the strip. I then advance the stripa second increment in length, locate the strip by engaging the secondpierced portion thereof, support the advance pierced portion of thestrip at longitudinelly spaced areas and leave alternateintermediateunsupported leg portions of the strip, and slit and bend theunsupported leg portions of the strip at right angles with respect tothe cross-bars thereof. I feed this strip a third increment in lengthand again locate and pierce the strip, slit and bend the unsupportedportions of the first successive section of the strip and finish bendthe advance unbent legs of the strip to providethe finished product. Ithen successively repeat the foregoing series of piercing, locating theslitting and bending and finish bending operations, performing theseoperations simultaneously at different longitudinally spaced placesalong the strip material, to continuously fabricate the strip materialinto a strip of U-shaped cross section with parallel spaced cross barsand parallel slit legs extending at right angles with respect thereto. Ialso maintain the strip in engagement with a bending die during theslitting and bending operation thereof, and exert sufficient atent2,834,096 Patented May 13, 1958 pressure thereagainst and against thedie to straighten and maintain the strip straight.

These and other objects of my invention will appear from time to time asthe following specification proceeds and with reference to theaccompanying drawings wherein:

Figure l is fragmentary end view of a punch press having a punch and dieassembly constructed in accordance with my invention associatedtherewith and looking toward the discharge end of the press;

Figure 2 is a fragmentary view in side elevation of the punch pressshown in Figure 1; I

Figure 3 is a plan view of the strip piston ring material showing thevarious operations performed thereon and the locations along the stripat which they are per view t'aken through the center of the punch anddie appa ratus and showing the discharge end thereof and forming ineffect a continuation of Figure 5; i v

Figure 7 is a fragmentary transverse sectional view taken substantiallyalong line VlI-VII of Figure 4;-

Figure 8 is a fragmentary transverse sectional view takensubstantiallyalong line VIII-VIII of Figure 4;

Figure 9 is a fragmentary transverse sectional view taken substantiallyalong line IXIX of Figure 4;

Figure 10 is a fragmentary transverse sectional view taken substantiallyalong lineX-X of Figure 4; and

Figure 11 is an enlarged detail end view ofthe punch and die assemblylooking toward the discharge end thereof. 7 V

The piston ring stock 10 formed in accordance with my invention is shownin Figure 3 in its several stages of completion, all of which areeifected in a single punching and forming operation from a flat strip ofsteel which may be high carbon steel such as SAE 1095 containing; 0.95%carbon. Said strip material may be in the form.

of a continuous strip unwound from a reel and fed to a punch press 11incorporating a punch and die assembly constructed in accordance with myinvention by means.

of a pair of intermittently rotating pinch rolls 12, 12 at the enteringend of said, punch press. Said pinch rolls may be driven from themechanism for operating the punch, head of the-press by a ratchetmechanism indicated gen, erally by reference character 13 and notshown'in detail since it is no part of my invention. Said ratchetmecha-' nism may be operated by an eccentric 14 andlink 15 operated fromthe drive shaft for the punch head. .The drive to said pinch rollsattained by said ratchet mechanism may be such as to feed the strip 10after. the

punches have been stripped therefrom and to hold said strip from feedingmovement during the punching opera.

ation.

The piston ring strip, as it enters the punch press 11, is firstrectangularly pierced at various aligned points therealong to provide aseries of equally spaced trans verse slots 16, 16 alongits center toform a ladder-like strip and leave a relatively rigid blank. The stripis then advanced through the punch and die assembly a'prede- 1 termineddistance and again pierced along its centerlf Upon the succeedingfeeding operations from the secondpiercing operation, the portion of thestrip which "has 1 previously'been pierced is then alternately slitandbent assesses downwardly, leaving alternate tabs 17, 17 extendingoutwardly from opposite sides of the central slotted portion thereof,and the leading portion of the strip previously pierced. slit and.alternately bent. downwardly is. then. given-a finish bendingoperationto form pistonringstoclc, of. urshaped fonnation hayinga.cen,tral ,unitormly slotted webwith" alternately slit crowns extendingtherefrom. inparallel'relationwithrespect to eachother. Thestoclt. soformed may then be formed into rings either directly from the punch anddie assembly or from a reel. (not shown} on which thecompleted stripstock may be coiled, inaccordancewith the method and: apparatusdisclosed in my application Serial No. 111,31 fi1cd;August, l 8 1949..

The punch press 11 is, shown in Figures 1 and 2 as being a well knownform ofreciprocating press, having a frame 20' with a pair of parallelspaced verticalguides 21; at the upper part, thereof and forming avertical'guide fora punch head'23; reciprocably moved'along said guide,by. a suitable reciprocating drive mechanism (not shown), and driven.from a transverse shaft 24 having the eccentric It at one end thereof.Said punch press, punch headj and'reciprocating drive mechanism may beof a formwell known to those skilledin the art and are no part of mypresent invention,. so herein shown and described only in sufficientdetail to make my present invention readily understandable. j v

I The punch head 23, has a plate 25" secured to its bottom and has afemale portion 26 of a dovetail guide extcndingl'ongitudinallytherealong and opening toward the groundi Said guide is adapted toreceive a corresponding male guide portion 27 of a punch shoe 29; Saidpunch shoe is guided for. vertical reciprocable movement on,longitudinally spaced pins 30, 30 projecting; upwardly from a die shoe3'1. Said die shoe is mounted. on and projects upwardly from a baseplate or table 32 for the punch press.

The punch shoe 29 depending from the plate 25" is herein shown as havinga downwardly opening channel 33 formed therein and extendinglongitudinally therealong from one end to the other. Said channel isadapted to receivea punch spacer 34' slotted at regular intervals toreceive and space apart a plurality of piercing punches 36 disposed atthe-entering end of the punch and die assembly, and a plurality oflocating or aligning punches- 37, 37' spaced in advance of said piercingpunches. Said punch spacer is abutted by a clamping member 35 which isalso mounted insaid channel, as will hereinaftermore clearlyappear asthis specification proceeds.

The channel 33- in the punch shoe 29 also has a clamp-- member 38mounted therein and, forming a: clampingmember for a plurality ofslitting and bending punches 39 39 disposed in advance of said piercingand locating punches and on opposite sides of the pierced or slot-tedportion of the strip for alternately slitting the strip on oppositesides thereof and bending alternate slit tabs 17 of the pierced stripdownwardly, leaving alternate tabs 17, 17 extending outwardly from thepierced portion of the strip. Said clamping member also has two finishforming or bending punches 40, 40 mounted therein: in alignment withsaid slitting and bending punches 39', 39 and spaced in advance thereoffor eifecting the finish bending operation on the strip and forming itinto a.

ing-punches 3.6, 36 during the punching operation. Said spacers. alsoform spacers; for locating dies- 46, for

the. locating punches. 37, 37. Said. piercing and locating a by machinescrews 53, 53 extending through, opposite 4. dies are held in positionin said spacer and inner die shoe by retaining or clamping members 49,49 extending along said spacers and recessed in -the channel 42 andengaging shoulder portions 50-50 of said dies. Flat-headed machinescrews 51, 51 are prov-idcdto secure said retaining members to saidspacers. Said spacers 44, 44 are securedtosaidachannel 42 formed in saidinnerdie shoe 41 sides, of,- said. die. shitev and threaded in thesides. of said spacers.

The piercing punches 36,36 are herein shown as abuttinga shim 54 whichmaybe; of varying thickness.- tovary the effective length of saidpunchesand which extends partially along the bottom of a punch pad 55 having a vertical leg 56 clamped between the punch spacer 34 and clampingmember 35.and; secured thereto as by machine screws 57, 57, securingsaid clamping member and spacer, together. An inclined locking bar- 59is adapted to engageinclined notched surfaces 60, 60 formed; in saidpiercing. and locating punches. Set screws 61, 61 threaded, in saidclamping member 35 are provided to. engage said locking bar and clampsaid piercing and:

locating. punches in said spacer. Said spacer 34 and clampingmember 35.are secured to thepunch holder 29 in the. channel 33 by machine screws62, 62- extending. throughthe top of said punch holder and recessedtherein andQthneadedir' said spacer and clamping member.

A stripper plate 6.4 is herein shown as being mounted forverticalfloating movement with respect tofthe, inner diev 41, on. guide, pins.63, 63 extending downwardly there from. and slidably. guided in saidinner die (Figures- 7 nd. Sa d' t inmr pl e ay t a plit. o t uc on;with, the parts thereof secured together by transversely. ex.- tendingmachinescrews 65, 65 having a plurality of spaced facing and registeringvertically extending slotsformed therein to provide piercing andlocating punch receiving slots 67,67 extending along the. center of saidplate and through which the piercing punches 36, 36 and locating punches37, 37 may reciprocably move. A plurality of compression springs 69,,69, are seated in upwardly opening spring-receiving sockets 70, '70formed in said inner die shoe 44 and abut the bottom of saidstripperplate 64 to support: and urge said stripper plate to move in a directionaway from said inner die shoe. Stops 71, 71 extend alongopposite sidesof said stripper plate and are secured to spring receiving sockets 75,75 formed in the top of said stripper plate 64. and project upwardlytherefrom wh n tree. Sa d. p i gs are h l o sai ripper. plate.

by machine, screws 76; 76. Said compression springs are heavier than thecompression springs 69, 69 and are adapted to be engaged by the bottomof the punch spacer 3'4' and punch clamp 35 upon downward movement ofthe punch head 23 -to move said stripper plate downwardly into,engagement with the flat strip piston ring material and to hold saidstripper plate into engagement therewith during the piercing thereof andas said piercing punches are withdrawn therefrom to strip said punchesfrom the pierced material and prevent deformation thereof,

Said compression springs 74, 74 are of suflicient strength to hold saidstripper plate in engagement with the strip material as the punch headmoves on its return path of travel and until the piercing punches 36, 36have beenstripped from the material.

The locating punches 37, 37' spaced in advance of the piercing puncheshave lower end portions converging to points andperform no punchingfunction. Said locat ing punches are mounted in the punch holder 35 in amannersimilar to which said piercing punches aremounted therein, and theconverging or pointed lower ends pierced in the piston ring materialupon downward movement of said locating punches in advance of saidpiercing punches to accurately locate the material at the beginning ofeach feeding operation and thus to assure uniform spacing of the slotspierced therein and also uniform spacing of the succeeding slitting andforming operations.

The channel 43 extending along the die shoe 31 has a die holder 79mounted therein in advance of the inner die shoe 41 and the piercing andlocating dies 45 and 46 respectively. Said die holder 79 has an opencentral portion 73 and has two similar die plates 80, 80 recessedtherein and extending over said open central portion 78 of said dieholder and secured to said die holder by machine screws 81, 31. Said dieplates are spaced apart at their inner ends and form a support for thestrip as it passes therealong. Said die plates 30, 80 have alternatelyarranged rectangular slots 33, 83 formed therein and opening toward eachother, the facing edges of which form slitting dies coacting with theslitting and bending punches 39, 39. The bending punches 39, 39 arearranged to alternately slit opposite sides of the strip and downwardlybend alternate slit portions thereof around a bending bar 85 eXtendingbetween said die plates and beyond the forward end thereof. The bendingbar 85 forms a slidable support and guide for the partially formed andfully formed strip (Figures 6 and 9). The portions of the die plates 30,80 in advance of the slots 83, 83 open toward each other and formelongated recesses or slots 86, 86 extending along each side of thebending bar 85 and adapted to receive the finish bending dies 40, 40 andthe remaining alternate tabs 17 of the strip material bent downwardly bysaid finish bending dies to form the finished piston ring stock to auniform U-shaped cross section.

The bending bar 85 is mounted within and extends upwardly from a base 87mounted in the open central portion 7 8 of the die holder 79 for limitedvertical movement with respect thereto (Figure 6). A plurality ofcompression springs 89, 39 seated in upwardly opening recesses 90, 90formed in the die shoe 31 abut the bottom of said base and urge saidbase and bending bar to move in an upward direction. Vertical movementof said base is limited by the projecting inner ends of the die plates80, 80.

The slitting and bending punches 39, 39 mounted in the clamping member38 abut a punch pad 91 at their upper ends and are laterally andlongitudinally spaced apart by means of a spacing member 92 carriedwithin said clamping member (Figures 9 and 10). Said punches are securedto said clamping member by set screws 95,

95 threaded therein and engaging inclined abutment sur faces of saidpunches. Said spacing and clamping member 38 is secured within thechannel 33 by machine screws 96, 96 threaded therein from the top of thepunch shoe 29 (Figures 6, 10 and ll).

The finish bending punches 40, 40 are mounted in the clamping member 33in advance of the punches 39, 39 on opposite sides of a spacing member99 extending from the spacer member 92 toward the discharge end of .themachine (Figures 6 and ll). Machine screws 104, 104, extending throughthe clamping member 38 and threaded in one side thereof and throughoutwardly facing slotted portions 105, 105 of said punches, serve tosecure said punches to said clamping member. Said finish bending punches40, 40 are notched at their bottoms, and the notched portions thereofopen toward the ground to form a plurality of teeth 106, 106 alternatelyarranged on opposite sides of said spacing bar 99 and engageable withthe alternate tabs 17, 17 to bend them downwardly about the bending bar85 and complete the formation of the piston strip stock.

A straightening bar 107 extends beneath the slitting and bending punches39, 39 and the finish bending punches 40, 40 for engagement with the topof the slotted strip prior to and during the'slitting andformingoperations thereon. Said straightening bar may best be seen inFigures 4, 6 and 11 and is yieldably suspended at its opposite ends onleaf springs 109, 109 extending transversely thereof and securedthereto, intermediate their ends, by machine screws 111, 111. The leafspring 109 at the discharge end of the punch press abuts the tops oflaterally spaced upright spacing members 113, 113 at its opposite endsand is secured thereto by means of a retaining member 114 clampedthereto by machine screws 115, 115 extending through said spacingmembers and threaded in said die shoe. In a like manner the leaf spring109 yieldably suspending the rear end of said straightening bar isclamped at its ends to the die shoe 31 in vertically spaced relationwith respect to the top surface thereof by a retaining member 117clamped to the ends of said leaf spring by machine screws 119, 119(Figure 10).

A plurality of spring-pressed plungers 121, 121 are slidably mounted inthe clamping member 38 at their upper ends and extend downwardly throughthe punch pad 91 and the spacing members 92 and 99 between the slittingand bending punches 39, 39 and the forming punches 40, 40 intoengagement with the top of the straightening bar 107 to yieldably engagesaid bar with the strip material during the slitting and bendingoperations thereof, as the punch head moves toward the die block 31. Asherein shown, each of said spring-pressed plungers has a cylindricalhead 122 of a piston-like formation slidably mounted in a drilledportion 123 of the clamping member 38. Compression springs 124, 124

mounted in said drilled portions of vsaid clamping menu her areinterposed between the bottom of the channel 33 and the top of the heads122' to yield upon downward movement of the punch head and to yieldablyengage said bending bar with the top of the strip prior to the slittingand bending operations thereof with sufficient force to straighten anybent portion of the strip and to hold said bending bar in engagementwith the strip until after the initial slitting and bending operationsand said slitting and bending punches have traveled away therefrom. Saidbending bar 85, as herein shown, is of a rectangular formation slightlynarrower than the web of the strip at the entering end of and beyond thedischarge end of the slitting and bending punches 39, 39. Thestraightening bar 107 has tabs 125, 125 extending alternately outwardlyfrom opposite sides thereof for engagement with the laterally extendingtabs 17, 17 of the strip.

The aligning guide for the strip, as it is pierced and passes beneaththe piercing punches 36, 36, is arranged to accurately align the stripduring the punching and feeding operations with no play and is formed bytwo laterally spaced guide plates 127,127 slidably engageable withopposite sides of the strip (Figures 4 and 5). Each guide plate 127 hastwo longitudinally spaced hearing pads 128, 128 engageable with thestrip prior to entering the region of the piercing and locating punches36 and 37 and after leaving said locating punches. Said guide plates areslidably supported adjacent their discharge ends on the top surface ofthe slitting and bending die plates 80, 80. Each of said guide plates127 has an outer vertical inclined engaging surface 129 inclinedinwardly from its discharge end toward the strip (Figure 4).

The inclined engaging surfaces 129, 129 of the guide plates 127, 127 areengaged by inclined cam surfaces 130, 130 of laterally spaced cammembers 131 having retaining flanges 132, 132 extending over the tops ofsaid guide plates. Said cam members are secured toand project upwardlyfrom the top surface of a transversely adjustable carrier member 133slidably guided in the die shoe 31. Set screws 134, 134 threaded inopposite depending ends 135, 135 of said carrier member, andengaging theouter sides of said die shoe 31, are provided to adjust said cam members130, 130 with respect to said die shoe and to center the guide and stripwith/respect to the respective punchesanddies' in the assembly. Clampingstrips, '136, 13,6extending over said carrier member, and clamped'inengagement'therewith, are provided to retain saidcarrier member tosaidguide shoe.

The ends of saidjguide plates adjacenttheentering end, of the punchpress slidably restgonthe top, surface 01 a, plate 137 projectingfromthe entering endof the, punchv anddie shoe 31 and, have inclinedengagingsurfaces 138, 138, like the inclinedtengaging surfaces 129, 129, whichare engaged by similar inclined camsurfaces 139, 139: of cammembers140,140, Saiicamimembersare mounted on and project upwardly, from,an,adjustable carrier: member 141, slidably-mountedjn a; transverseslot- 142, formed in thettop surfaceoftheplate 137: Said-carrier memberlikewise has depending outer end;- portions through. which extend setscrews: 1,44-, 144,; to afford a me j t ng: e positi n; f; id: nclin d?cant; surfaces 139; 139; and; toy center said-guide plates 127,- 127,with respectrto the; dies, 45, 45.v Clampingstrips; 145', 145 are,provided tolclamp said:carrier member in; position.

The ends of guide plates 127,127 adjacent the entering: end of themachine have: trunnion supports :146; 146 pro-- jecting upwardlytherefrom; A transver se pin 14 /",mounted'attits-endsin said trunnionsupports,- is herein-shown as= extending through a boss 148- formed---integrally-- with the'head end of'ahollow-cylinder 149 -and as beingsecured thereto asby a set screw 150. Said cylinder isslidably mounted Iwithin the a cylindrical inner portion of: a boss 151 for extensiblemovement therefrom; A spring 152 seated within said'cylinderl49is-interposed between the closedhead end of said=cylinder-anda'plosureplate 153for said boss; and tends to urge-saidcyfim der 149 and theguide plates 127', 127 toward theentering end of the machine, andthus tomore saidgujde, plates along the cam surfaces v1330, 13:0v andil3'9il39in a direction to engage thebearing-pads 128,128 with opposite sidesof the strip at points spaced longitudinally therealong. The boss 151 isherein. shown as" being formed integrally withand projecting upwardlyfrom a bracket 154 secured to the; plate 137 on opposite, sides of saidguide plates,127, 127and asextending ovensaid" guideplates and. thestrip passing through the punch When the stripis stationary, theguideformedlby the guide plates 127,127 engaging oppositesides-oi the stripat longitudinally spacedpoints is thus engagediwiththe strip to hold itin positionwith no play, by the compressionspring'llSZ urging saidguideplates-to move toward the entering end ofthermachine against'thecamsurfaces 130, 130 and 139 139, moving said-guide-plates;127; 127 intoengagement with the strip.

When, however, the strip is fed through th'emachineby the pinch rolls12', 12 the tendency willb'e for the guide plates 127', 127 to movewiththestrip againstthefcom: pression spring 152i Movement of said guideplates in this direction will compress-said; spring and allow said guideplates to move along the camsurfaces 130,130

and139, 13 in adirectionjo releasesaidggllide plates,

fromthe strip. Under thiscondition, saidguideplates;

locating punches-3,6, ;3.6i:;;an d,37, 37 and to the-slittingmndr anceagainst the strip during travel through the machine and forms aself-aligning guide' means therefor.-

Thepiston ring stockmay be produced by; taking a coil o f--pistonringstrip-material 10' eithe -required"width andfeedingthe material'throughthe pinch rolls 12; 12' from a suitable reel; (not shown), under a guidestrip 155'at the entering end of the machineand along the plate 137into-engagement with the bearing pads 128, 128 of the'guide-plates 1'27holdingthestrip in centered relation with respect to'the piercingpunches 36, 36. For; thefirst piercingoperationthe-strip may be trainedby handunder to effect thefirst piercing-operation by-yertical'downward'movement-'ofthe; punch heador term 23; the punches 36,, 36'punchingrectangular-slugs 156, 156 from'the'strip at equally spacedintervalsthrough the dies 45, 45; where-said slugs may drop throughthedie assembly to the ground or to a suitablereceptacie therefor(Figure 8). After the first punchingoperation the stripper plate G t-isheld in firm engagement with the strip by the springs 74', 7,4 tostripthe piercing punches 36, 36 therefrom and hold thev strip fromdeformation during return travel of said punches: path asufiicientdistance to be free from the strip, the

pinch-rolls- 12, 12 will then be rotatably driven through. the eccentric14-and pawland ratchet drive 13to feed the strip longitudinally adistance Which-may be equal'to,

16 pierced in the strip prior to engagement ofthe piercingpunchestherewith to accurately locate the strip. with respect to said slotsandassure an even spacing of the second group of slots pierced in thestrip after the second, The strip may again'be advanced punchingoperation. through the machine andits leading end may passbeneath thestraightening bar 107in position-to be straightened, therebyand tobealternately slit'andbent 0n opp osite sides of the slots; 16, 16 bythe slittingandforming or bending punches 39, 39. During this operation,the straighteningbar 107 first comes into engagement with the topsurface of the strip to-straightentany, deformation, thereof and to holdit from undesired deformation during v the slitting and bendingoperation, said :straightening, bar servingas a stripper during, thereturn traveliof said' slitting and bending punches39, 39; After theinitial bending operation, alternate downwardly, bent tabs,,17, 17willslidably engage opposite-sides of the bending bar 85,which-will=form a;self-aligning guide for the strip as it passes to thedischarge end of the punch. During returnv travelof the punch headjZ3thestrip will again be advanced'adistance which may be determined'by thespace between the outside of the first and last piercingpunches 36, 36plus the space between two of saidypunches, and'thealternatelyprojecting tabs 17', 17 may then be formedor-bent-downwardly over the bending bar 35 ito form the-leading end ofthe strip intovpiston ring stock substan'tially U-shaped in crosssection and having agcentral uniformly slotted web with alternatelyslit'parallel spaced crownsextending along opposite sides, thereof;'andsub.- stantially perpendicular to said web, 10.

Irmaybe'understood'from the foregoing thataften the leading endof thestrip has once been properly formed into piston, ring stock of U-shapedcross section that,

the stock ofjthe proper cross section may beintermittentlydischarged'jrom the. discharge end of the machine andthatthe piercing,locating, slitting andbending, and

When-said punches have movedpn their return 9 finish bending operationsare all efiected simultaneously upon each downward stroke of the diehead 23 at successive points along the strip.

It will be understood that modifications and variations may be etfectedwithout departing from the scope of the novel concepts of the presentinvention.

I claim as my invention:

The method of fabricating a channel shaped ladderlike metal strip whichcomprises simultaneously piercing a plurality of longitudinally spacedparallel transverse slots along the longitudinal central portion of theadvance end of the strip to produce a ladder-like blank withlongitudinal side legs and spaced transverse cross portions connectingthe legs together in a plurality of successive piercing operations alongthe length of the strip, and during the second piercing operationlocating the strip by engagement with the pierced portions thereof, thenadvancing the pierced strip and supporting the legs of an advanceincrement in length of the pierced strip at longitudinally spaced areasand leaving alternate portions of the opposite side legs unsupported instaggered relation with respect to each other, then in a third operationsimultaneously piercing and locating the strip by engaging the piercedportions of a next succeeding length of strip and holding down andstraightening the supported leg portions and transversely shearing theunsupported leg portions from the supported portions and in the sameoperation bending the unsupported leg portions to form downwardly benttabs staggered with respect to each other on each side of the strip,advancing the resulting sheared and alternately bend strip to move 1dthe remaining unbent leg portions beyond the supports therefore andduring the advancing operation guiding the strip on the alternately bentleg portions, and then in a fourth operation simultaneously piercing andlocating next succeeding increments in length of strip and holding downthe supported leg portions and shearing and alternately slitting andbending the unsupported leg portions of an increment in length of thestrip in advance of the length pierced and at the same time bending theunbent leg portions of an increment in length of the strip in advance ofthe increment in length being slit and bent into alignment with the bentleg portions of an advance increment in length of the strip to form a.

channel-like strip, and then continuing advance of the strip andsimultaneous piercing, locating, shearing holding down and alternatebending and finish bending and guiding operations at spaced equalincrements in length of the strip throughout the length of the strip, tocontinuously produce a channel-like strip having a ladder-like web andslit legs extending therefrom.

References Cited in the file of this patent UNITED STATES PATENTS1,424,831 Kux Aug. 8, 1922 1,915,531 Irmis June 27, 1933 1,925,034Fitzgerald Aug. 29, 1933 2,043,919 Bengston June 9, 1936 2,201,316 McGeeMay 21, 1940 2,311,728 Bowers Feb. 23, 1943 2,311,729 Bowers Feb. 23,1943

